Windows 2000 Server supports two licensing modes: per server and per seat. With the per-server licensing mode, you must add client access licenses (CALs) for specific server products, such as Exchange Server or Windows 2000 Server itself (for general client access to the server).

In per-server mode, the server application compares the number of concurrent connections to the server against the number of CALs listed in the Licensing console and denies access when the number of
connections reaches the number of CALs.

In per-seat mode, you must purchase a CAL for each computer that will access the server, but Windows does not track connections against CALs in the Licensing console.

Per-seat licensing allows client connections to servers configured for per-seat licensing, but there's no guarantee that a client can connect to a server application configured for per-server licensing. Server applications configured for per-server licensing will still need to have CALs added through the Licensing console even if you've configured the server for per-seat licensing.

In addition to using the Licensing console to add CALs for specific products, you can also use it to switch from per-server to per-seat modes for a given server application. This change is one-way, and you'll only be able to make the change once.

To change licensing modes, open the Licensing console. On the Server Browser tab, expand the server, and double-click the server application. Select Per Seat, and click OK.